We're experiencing a grey slime buildup in our trickling filters and SBRs, which we've never experienced before. The BOD reduction in our trickling filters have decreased by 20%, thinking it is due to the slime. We're also seeing bulking and slow settling in our SBRs. We tried increasing the MLSS concentration without success and have increased settle time with success, but the sludge is still slow settling in the SBRs. We are a municipal plant with the majority of industrial loading. pop, milk, ice cream, eggs, milk whey.